Dynamo-electric machine



(No Model.)

H. E. WALTER, DYNAMO ELEGTRIG MACHINE.

No. 403,158. Patented May 14, 1889.

nun 1 UNITED STATES PATENT OFFICE.

HENRY E. IVALTER, OF SOHENECTADY, NFHV YORK.

DYNAMO-ELECTRIC MACHINE.

SPECIFICATION forming part of Letters Patent No. 403,158, dated May 14, 1889.

Application filed April 21, 1888. Serial No. 271,493. (No model.)

To aZZ whom it may concern:

Be it known that I, HENRY E. \VALTER, a subject of the Queen of Great Britain, residing at Schenectady, in the county of Schenectady and State of New York, have invented a certain new and useful Improvement in Dynamo-Electric Machinery, of which the following is a specification.

The object of my invention is to avoid the necessity of shifting the commutator-brushes of dynamo-electric generators and electro-dynamic motors by maintaining the non-sparking points of the commutator constantly at the same position. In such machines when there is a current in the armature the position of the poles in the armature set up by the main field-magnet is changed by the m agnetism of the armature, which makes the poles of the armature and also the field-magnet poles or pole-pieces the resultant of its own magnetism and that of the field-magnet, and if the brushes are shifted toward the new neutral point the consequent change of posiion of the magnetism of the armature makes the effect- 011 the armature and the field-magnet poles still greater.

To avoid the shifting and to maintain a constant non-sparking point is the object of my invention, which consists, mainly, in providing an extra regulating magnet or magnets acting on the end or .ends of the armature outside the main field-magn et pole-pieces. In the preferred form of my invention I place such regulating-magnets at each end of the armature, so as to avoid an end pull on the armature. These magnets I wind with coils, which receive the whole or a proportional part of the armature-current, so that the effeet on the armature varies with its current. I so place the extra magnet that its poles extend from at or near the middle points between the main pole-piecesor the neutral points at no loadon the armature to nearly half-way around the main pole-pieces on each side. In this position the magnetism of these extra magnets first neutralizes the magnetism in the ends of the armature due to the armature-current, then generates inthe coils sh ortcircuited by the brushes an electro-motive force sufficient to overcome that generated in the middle of a coil, and also as much more QlGOflO-lllOlllVfl force as is necessary to create a current in the coils as they leave the brushes equal in strength and direction to that which they will have to carry after having left the brushes. From these effects it follows that with the brushes once adjusted to the non-sparkin g points they will not have to be moved again. The extra magnet also tends to assist the magnetism of those parts of the main field which are weakened by the armature magnetism, and thus raises the total effective magnetism of the machine; and as this effect increases with the armature-current or load on the machine it tends to make the electro-motive force in the armature more nearly uniform than is ordinarily the case. In large machines the effect of this may be to over-compound the machine. I therefore in such machines prefer to provide on the main field-magnet a small extra differentiallywound coil in series with the armature to counteract this excessive effect of the regulating-magnet. These are the main features of my invent-ion, which, with others of less importance, are illustrated in the accompanying drawings, in which- Figure 1 is a front view of a dynamo-electric machine constructed according to one form of my invention; Fig. 2, a side view of the same; Fig. 3, a diagram illustrating the connections. Figs. at and 5 show two ways in which my invention may be used with a motor. Figs. 6 and 7 are front and side views showing another form of regulating-magnets. Fig. 8 shows an arrangement for the Siemens form of field -1nagnet. Fig. 9 shows an arrangement for a multipolar machine. Figs. 10 and 11 illustrate another form for the regulating-magnets, Fig. 10 being a front view and Fig. 11 a top view; and Figs. 12 and 13 similarly illustrate still another form.

Referring first to Figs. 1, i3, and 3, A represents the field-magnet, having pole-pieces N S, and B is the armature of a dynamoelectrie machine. 1 2 is the main circuit, and 3 i the field-shunt.

Suitably supported upon the base-plate of the machine at each end of the armature is a small magnet, G, whose poles N Sact upon the ends of the armature outside the poles of the main field-magnet, and which assist the main poles extending from the middle points or neutral line at no load around nearly halfway on each side, so as to coincide with those corners of the main poles which are weakened by the armature magnetism. The magnets 0 are connected in series with the armature.

In Fig. 3, principally for convenience in showing the circuits, only one magnet in shown. This is a form which may be used, though I usually prefer to provide a magnet at each end of the armature. The effect of this magnet or magnets is partially illustrated in Fig. 1. The neutral line at no load without the extra magnets is indicated by a a. The line due to the resultant of the main field and armature magnetism is shown at Z) Z), and the actual neutral line with my invention is at c c. This line is practically constant in position, because its tendency to vary from changes in the armature magnetism due to changes in current in the armature is counteracted by the regulating-magnets whose magnetism is changed by the same current.

To originally adjust the machine to a constant non-sparking point the regulating-magnets may be shunted or cut out of circuit. In order to avoid leakage of magnetism when there is no current in the coils of these magnets, I separate their poles from the main poles far enough to prevent much leakage across the space between them.

It will be seen that at the same time that the extra magnets neutralize the armature magnetism they also generate in the armature-coils an electro-motive, force which neutralizes the self-induction and prevents the sparking consequent thereon. They also equalize the total field magnetism as the armature current or load increases, and therefore tend to produce a constant -potential generator or a constant-speed motor. As above stated, in large machines there will be an excessive effect in this way, the change of field strength being too great, and I therefore add to the main field-magnets extra differentially-wound coils D, also in series with the armature, and by properly proportioning these coils and the extra magnets the machine can be made self-regulating.

In motors the poles of the extra magnets may be made either to assist or to oppose those of the main field-magnet. The former arrangement is shown in Fig. 4:, where the effect is as already explained, and the extra series coil on the main magnet will have a current opposite in direction to the shunt or main field-coils. The latter arrangement is indicated in Fig. 5. Here the extra magnets tend to weaken the effect of the main magnets, and to make a constant-speed motor the extra series coil on the main magnet must have a current in a direction such as to assist the shunt-coil and to oppose the extra magnets.

In Figs. 6 and 7 the extra magnets are shown as in the form of rings wound with coils in series with the armature at (Z (Z, and hav- I is shown in Figs. 10 and 11.

ing poles N S in the-right position to give the desired effect, as above described.

Fig. 8 shows an arrangement for a Siemens form of field-magnet. The extra magnet isa ring wound with coils cl d and having poles N S assisting the main poles N S. I

Fig. 9 shows a'multipolar dynamo with alternating north and south poles, N S NS. The extra magnet is a ring with coils d d and poles at N S N S assisting the main poles. they being placed in corresponding positions to those of the extra magnets in the bipolar machines above described.

I may in some cases wind the extra magnets with both shunt and series coils, so that they act to compound the machine and not to over-compound it, and also to prevent sparking, in the manner above described. In this case I may employ two magnets of equal size, one being the main magnet, which will be shunt-wound, the other, the regulating-magnet, having both shunt and series coils, or I may have the large main shunt-wound magnet in the middle and two magnets each about half the size of the main magnet, one at each end of the armature and each wound partly in shunt and partly in series. The latter form The extra magnets 0 O are suitably supported by zinc blocks 2', and are wound partly in shunt and partly in series, as shown. The main pole pieces N S at their weakened portions are cutaway, so as to recede from the armature, and at these points the extra pole-pieces project so as to predominate. They act in substantially the same manner as already explained.-

In the form. shown in Figs. 12 and 13 (Fig. 12 being a rear view) the magnets A and O are equal in size, magnet A being in shunt and magnet 0 being partly shunt and partly series wound. The poles of these magnets are arranged as shown, the poles N S receding and the poles N S advancing at points where the effect of the armature magnetism is greatest, the effective poles of the two ma nets being thus practically set at an angle to each other as they are in the preceding forms of my invention.

What I claim is-- 1. In a dynamo-electric machine, the com bination, with the armature and main fieldmagnet, of an extra magnet having coils in series with the armature and acting on the armature-coils outside of the main field of force, substantially as set forth.

2. In a dynamo-electric machine, the combination, with the armature and main fieldmagnet, of two extra magnets, each having coils in series with the armature and acting upon the armature-coils at opposite ends of the armature and outside of the main field of force, substantially as set forth.

3. In a dynamo-electric machine, the combination, with the armature and main fieldmagnet, of an extra magnet having coils in series with the armature whose poles are situated so as to act upon the armature-coils outside of the main field of force and so as to assist the parts of the main magnet-poles which are weakened by the armature magnetism, substantially as set forth.

4. I11 a dyi'iamo-electric machine, the combination, with the armature and main fieldmagnet, of the extra magnet having coils in series with the armature and actingupon the armature-coils outside of the main field of force, the effective poles of the main magnet and extra magnet being situated so as to act upon the armature at an angle with each other, substantially as set forth.

5. In a dynamo-electric machine, the combination of the armature, the field-magnet, and the extra magnet acting on the armature-coils outside the main field of force and Wound partly in series and partly in shunt with the armature, substantially as set forth.

6. In a dynamo-electric machine, the combination of the ari'nature, the field-magnet, an extra magnet having coils in series with the armature and situated so as to prevent selfinduction in the armature-coils, and an extra coil on the field-magnet in series with the armature, substantially as set forth.

This specification signed and witnessed this 31st day of March, 1888.

HENRY E. XVALTER.

\Vitnesses:

WILLIAM. PELznn, A. \V. KIDDLE. 

